The relationship between mean wing length and density of gypsy moth,Lymantria dispar(L.), is described for leading-edge populations in Virginia and Maryland. Mean number of moths per trap, egg mass density, and eggs per mass in the succeeding generation were all related to mean male moth wing length using regression and correlation analyses. Because of the variability in egg mass density, predictions derived from regression models should be viewed as a part of a sequential approach to quantifying gypsy moth populations in management programs. Wing length estimates can assist in establishing priorities for egg mass surveys in a pheromone trap-based monitoring system. The use of wing lengths together with other density measures of gypsy moth populations can provide managers with additional information and put into use a measure of population quality for gypsy moth management decisions.